The prior art has evolved a number of chimney fire extinguishers. These typically provide a source of pressurized extinguishate and a conduit for conveying extinguishate from the source to a sprinkler head or nozzle which discharges the extinguishate into the chimney. U.S. Pat. No. 4,341,267 issued July 27, 1982 for an invention of Guy Lagasse is typical of the prior art. Lagasse provides what appears to be a conventional building type sprinkler head which is normally held closed by a link "made of a metal with a low melting point so that it melts at a temperature that is symptomatic of fire in the chimney". Unfortunately, the fusible links incorporated in conventional building fire sprinklers are not capable of remaining intact when exposed to temperatures in excess of about 500.degree. F. However, temperatures exceeding 500.degree. F. are often encountered in chimneys, although such temperatures are not considered to be symptomatic of fire conditions within the chimney unless they exceed 1000.degree. F. Accordingly, prior art arrangements of the type exemplified by the Lagasse patent are prone to false alarm triggering and consequential damage and disruption within the premises associated with the chimney.
Canadian Pat. No. 1,161,805 issued Feb. 7, 1984 for an invention of Stephen Aderneck further exemplifies the prior art. Aderneck provides a discharge nozzle which is positioned within the chimney. When Aderneck's apparatus is triggered (again by the melting of a fusible link, which also appears to be prone to false alarm triggering for the reasons given above) extinguishate is discharged through the nozzle and forced down the chimney. Aderneck's arrangement will apparently discharge a relatively large volume of liquid extinguishate down the chimney. This is disadvantageous for several reasons. First, the relatively heavy liquid extinguishate material will be forced down the chimney in a relatively short time span, thus removing the extinguishate from the chimney fire area in which it is needed to extinguish the fire. Second, experience has shown that chimney fires cannot always be extinguished by subjecting them to relatively short bursts of liquid extinguishate; rather, reasonably prolonged application of extinguishate is required to extinguish many chimney fires. The relatively small quantity of extinguishate available in pressurized extinguishate sources normally intended for coupling to chimney fire extinguishing systems is unfortunately rapidly exhausted when discharged as a liquid stream through prior art arrangements of the type just described. The inventors have found that a preferable technique is to spray a relatively fine mist of extinguishate up into the chimney where it may hover for a reasonably prolonged time in the vicinity of the fire, thus maximizing the fire extinguishing action. All too often, prior art arrangements of the sort described above apply relatively little extinguishate to the chimney fire, the bulk of the extinguishate material passing down the chimney without affecting the chimney fire, but falling onto the fire in the grate, thereby generating large quantities of smoke which may impede efforts to extinguish the fire, and cause smoke or liquid damage to the premises associated with the chimney.
A further significant disadvantage of prior art arrangements of the type hereinbefore described is that they are awkward to install and remove. For example, the Lagasse apparatus is apparently preferably mounted at the top of the chimney on a support bracket fixed to the outside wall of the chimney. This is rather unsightly, renders the apparatus relatively inaccessable and exposes it to the elements. Aderneck provides a variety of support brackets for holding the various components of his system in their intended positions. This arrangement is also relatively cumbersome to install and service.
The applicant provides a chimney fire extinguisher which overcomes the foregoing disadvantages. More particularly, the applicant provides a novel sprinkler head for discharging a fine mist of extinguishate material up into the chimney for maximal effect in extinguishing chimney fires. The extinguishate material is normally prevented from passing through the sprinkler head by a fusible sealing means which does not melt until chimney temperatures on the order of 1200.degree. F. are attained, thereby minimizing possible false triggering of the apparatus. The applicant's apparatus is also constructed for removable insertion through a relatively small aperture in a wall of the chimney. This arrangement facilitates rapid removal of the apparatus for servicing of the apparatus or for cleaning the chimney and also ensures location of the sprinkler head in a preselected position from which extinguishate may be discharged into the chimney for maximal fire extinguishing effect.